1. Field of the Invention
The present invention relates generally to a cast for orthopedic leg injuries, and more particularly to an inflatable cast having a plurality of adjustable pressure air chambers contained within a resilient outer support casing which may easily be installed around a patient's lower extremity to control tissue edema and minor undisplaced fractures, acute sprains, and ruptures of supporting ligaments.
The traditional techniques of treating orthopedic leg injuries have revolved around three type of devices: casts, which have application primarily in broken legs; splints, which are utilized to immobilize and stabilize injuries; and pressure bandages, which are used both to control swelling and to present a degree of support, particularly to ankles. Splints and elastic bandages are often used in conjunction with each other. As in other areas of medicine, creative individuals have come up with a variety of departures from these standard themes in order to present better techniques of patient treatment.
One of the first alternative devices is taught in U.S. Pat. No. 3,561,435, to Nicholson. The Nicholson apparatus is an inflatable splint which holds a cooling medium, such as crushed ice, on its interior side. The inflatable splint fits over the patients lower leg, and is inflated both to stiffen the splint and to bring the cooling interior surface of the splint into intimate contact with the patient's leg. The Nicholson device is designed to be used only temporarily rather than over an extended period.
Another variation on the theme of a cast is illustrated in U.S. Pat. No. 3,643,656, to Young et al., and in U.S. Pat. No. 4,817,590, to Stancik, Jr. These devices are both one-time inflatable casts, which are each applied in similar fashion to a patient's lower leg in a loose-fitting manner. Following the initial installation, they both have an inflatable compartment for placement adjacent the patient's leg located in the interior of the cast filled with foam to closely fit against the patient's leg.
Young et al. uses the introduction of a foam-producing substance into the inflatable compartment to provide the close fit. Stancik, Jr. injects a material which hardens in the inflatable compartment, in a manner similar to that of the Young et al. reference.
These devices have a drawback which limits their application considerably. Both the Young et al. and the Stancik, Jr. devices are essentially replacements for a fixed shape cast, in that once the foam sets they will be in a fixed configuration. Thus, their only application is as a replacement for a fixed cast, and due to their added cost and lack of additional advantages they present no substantial advantage over standard casts. Additionally, they are inapplicable in situations where there is any substantial tissue swelling. Finally, they provide no support for the ankle, other than the mere presence of the inflatable compartments.
The problem of providing a variable and changeable inner configuration is solved at least in part through the use of an inflatable cast apparatus, with air-inflated inner chambers being used to place pressure on the leg. Such devices are disclosed in U.S. Pat. No. 3,580,248, to Larson, in U.S. Pat. No. 3,786,805, to Tourin, and in U.S. Pat. No. 3,955,565, to Johnson, Jr. The Larson and Johnson, Jr. '565 devices are remarkably similar, both having front and back hard shells which are fastened together with hardware (Larson) or straps (Johnson, Jr. '565) to enclose the lower leg and foot.
The Larson device has inflatable liners in each shell half covering the entire lower leg and most of the foot, while the Johnson, Jr. '565 device has inflatable air bags in each shell half extending the length of the lower leg. They both offer little adjustment for different size legs other than the inflatable compartments, and are really designed mainly to immobilize a patient's leg. They also provide no particular support for the ankle other the mere existence of the inflatable compartments, which provide little ankle support.
Differing somewhat from these hard shell designs is the Tourin apparatus, which has more parts than any of the other devices of this type known. Rather than using hard shells, the Tourin device uses a complex frame having front and back inflatable cushions supported from a frame. Tourin suffers some of the same deficiencies as the Larson and Johnson, Jr. '565 devices, and adds substantially to these deficiencies with its complexity, undoubted high cost of manufacture, and its difficulty of assembly.
As might be expected, the art has more recently produced devices which, although completely different, do provide ankle support alone. U.S. Pat. No. 4,628,945, to Johnson, Jr. (the same Johnson, Jr. as in the '565 patent) and U.S. Pat. No. 4,977,891, to Grim are examples of ankle braces using inflatable compartments. Johnson, Jr. '945 uses shell members with inflatable, partially foam-filled liners to provide ankle support, while Grim uses an ankle brace with inflatable bladders which are pumped up when the wearer walks or runs. Both devices are only suitable for ankle support, and are not intended for the same applications as that of the present invention.
It is accordingly the primary objective of the present invention that it provide an improved cast apparatus having inflatable cushioning support for the leg of a patient. As such, it is an objective that the inflatable cushioning for the patient's leg should be adjustable in pressure at any point in time over the entire period of use by the patient to allow the pressure to be used to control edema after the initial occurrence of an injury, and to provide continuing support as the healing process continues. The mechanism for providing the pressure to the cast apparatus should be easy and convenient to use, as well as being capable of precision in its operation to precisely adjust the pressure on the patient's leg.
It is a further objective of the cast apparatus of the present invention that it provide ankle support specifically designed for the ankle instead of mere air cushions which happen to bear in part against the ankle. The ankle support apparatus must be fully integrated in the cast apparatus of the present invention, and must further be capable of pressure adjustment independently of the inflatable cushioning provided for the leg of the patient.
It is yet another objective of the cast apparatus of the present invention that it be capable of providing support and cushioning for the foot of the patient. In addition to restricting the degree of movement and providing support for the patient's foot, the cast apparatus of the present invention should also present foot cushioning allowing the patient (with the approval of his of her physician) to place weight on the leg supported by the cast apparatus of the present invention. Like the ankle support apparatus, the foot cushioning and support apparatus must be fully integrated in the cast apparatus of the present invention, and must further be capable of pressure adjustment independently of the inflatable leg cushioning and the ankle support apparatus.
It is an additional objective of the adjustable cast of the present invention that it be easy both to install and to adjust on the leg of a patient. It should also be manufacturable of lightweight, non-rigid material which is both tough and durable to afford it excellent strength and durability. It is a further objective of the cast apparatus of the present invention that it offer the ability to use one or more rigid splints if desired, with the splints being easily installable in integrated fashion into the cast apparatus. Finally, it is also an objective that all of the aforesaid advantages and objectives of the present invention be achieved without incurring any substantial relative disadvantage.
It should be noted that this invention can readily be applied to other extremities, including the arm, wrist and hand, and should not be considered as limited to a leg and foot.